<!DOCTYPE html>
<head>
    <meta charset="UTF-8">
    <title>div练习</title>
 
    <style>
        /* 三栏布局，中间自适应高度... */
       
        * {
            margin: 0;
            padding: 0;
        }    
        .head{
            height: 100px;
            width: 100%;
            background-color: gold;
            text-align: center;
            
        }
        .container{
            position: absolute;
            width: 100%;
            display: flex;
            top: 100px;
            bottom: 100px;
        }
        .left-group, .right-group{
            width: 200px;
            background-color: #7ecff2;
            text-align: center;
              
        }
        .mid-group{
            flex: 1;
            background-color: #ff5000;
            text-align: center;
            background-image: url(img/rdj_mid.jpg);
        }
        .foot{
            position: absolute;
            width: 100%;
            height: 100px;
            bottom: 0;
            background-color: purple;
            text-align: center;
        }
    </style>
 
</head>
<body>
 
      <div class="content">
           <div class="head">head</div>
           <div class="container">
                <div class="left-group">left-group</div>
                <div class="mid-group">mid-group</div>
                <div class="right-group">right-group</div>
           </div>
           <div class="foot">foot</div>
      </div>
    
</body>
</html>